The present invention relates to an electrical machine with two axial fans.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Electrical machines (especially electric motors and generators) frequently possess a cooling system with a fan and a fan cowl for optimizing the dissipation of heat. The fan sucks in the cooling air, which is then blown onto the electrical machine via cooling ribs of the housing. For a good cooling effect a sufficient volume of air or volume of cooling medium must be conveyed.
The cooling of electrical machines is possible with different fans. For example radial fans and axial fans can be used for cooling, which are mounted directly on the motor shaft. Radial fans have fan blades which extend radially outwards and which are likewise designed to convey the cooling medium radially outwards. The conveyance of the cooling medium by radial fans is independent of the direction of rotation of the electrical machine.
With axial fans the fan blades are attached with a specific inclination to the fan boss. The axial fan conveys the cooling medium in the axial direction. The direction of conveyance however depends upon the direction of rotation of the shaft and on the direction of inclination of the fan blades. Generally the axial fan conveys more cooling medium than the radial fan. To utilize the advantages of axial fans (high-volume airflow and low noise) the fans have previously always had to be tailored to the direction of rotation of the electrical machine.
In addition it is possible to cool an electrical machine with the aid of an external fan. External fans are generally embodied as axial fans. They have their own drive with a fixed direction of rotation. Therefore the cooling is undertaken independently of the direction of rotation of the shaft of the electrical machine. However external fans always require their own drive.
It would therefore be desirable and advantageous to provide an improved electrical machine in which independent of the direction of rotation, a highly effective cooling of the electrical machine is achieved while the required installation space is reduced as much as possible.